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October 4, 2000 LBNL-44712

From Quantum Nonlocality to Mind-Brain Interaction∗

Henry P. Stapp

Lawrence Berkeley National Laboratory

University of California

Berkeley, California 94720

Abstract

Orthodox Copenhagen quantum theory renounces the quest to un-

derstand the reality in which we are imbedded, and settles for practical

rules that describe connections between our observations. However,

an examination of certain nonlocal features of quantum theory sug-

gests that the perceived need for this renunciation was due to the

uncritical importation from classical physics of a crippling metaphys-

ical prejudice, and that rejection of that prejudice opens the way to a

dynamical theory of the interaction between mind and brain that has

significant explanatory power.

∗This work is supported in part by the Director, Office of Science, Office of High Energy

and Nuclear Physics, Division of High Energy Physics, of the U.S. Department of Energy

under Contract DE-AC03-76SF00098

“Nonlocality gets more real”. This is the provocative title of a recent

report in Physics Today (1998). Three experiments are cited. All three

confirm to high accuracy the predictions of quantum theory in experiments

that suggest the occurrence of an instantaneous action over a large distance.

The most spectacular of the three experiments begins with the production

of pairs of photons in a lab in downtown Geneva. For some of these pairs,

one member is sent by optical fiber to the village of Bellevue, while the other

is sent to the town of Bernex. The two towns lie more than 10 kilometers

apart. Experiments on the arriving photons are performed in both villages at

essentially the same time. What is found is this: The observed connections

between the outcomes of these experiments defy explanation in terms of

ordinary ideas about the nature of the physical world on the scale of directly

observable objects. This conclusion is announced in opening sentence of the

report (Tittle et al. 1998) that describes the experiment: “Quantum theory

is nonlocal”.

This observed effect is not just an academic matter. A possible appli-

cation of interest to the Swiss is this: The effect can be used in principle

to transfer banking records over large distances in a secure way (Tittle et

al. 1999). But of far greater importance to physicists is its relevance to two

fundamental questions: What is the nature of physical reality? What is the

form of basic physical theory?

The answers to these questions depend crucially on the nature of physical

causation. Isaac Newton erected his theory of gravity on the idea of instant

action at a distance. According to Newton’s theory, if a person were to

suddenly kick a stone, and send it flying off in some direction, every particle

in the entire universe would immediately begin to feel the effect of that kick.

Thus, in Newton’s theory, every part of the universe is instantly linked,

causally, to every other part. To even think about such an instantaneous

action one needs the idea of the instant of time “now”, and a sequence of

such instants each extending over the entire universe.

This idea that what a person does in one place could instantly affect

1

physical reality in a faraway place is a mind-boggling notion, and it was

banished from classical physics by Einstein’s theory of relativity. But the

idea resurfaced at the quantum level in the debate between Einstein and

Bohr. Einstein objected to the “mysterious action at a distance”, which

quantum theory seemed to entail, but Bohr defended “the necessity of a final

renunciation of the classical ideal of causality and a radical revision of our

attitude towards the problem of physical reality”(Bohr 1935).

The essence of this radical revision was explained by Dirac at the 1927

Solvay conference (Dirac 1928). He insisted on the restriction of the appli-

cation of quantum theory to our knowledge of a system, rather than to the

system itself. Thus physical theory became converted from a theory about

‘physically reality’, as it had formerly been understood, into a theory about

human knowledge.

This view is encapsulated in Heisenberg’s famous statement (Heisenberg

1958):

“The conception of the objective reality of the elementary particles has

thus evaporated not into the cloud of some obscure new reality concept, but

into the transparent clarity of a mathematics that represents no longer the

behaviour of the particle but rather our knowledge of this behaviour.”

This conception of quantum theory, espoused by Bohr, Dirac, and Heisen-

berg, is called the Copenhagen interpretation. It is essentially subjective and

epistemological, because the basic reality of the theory is ‘our knowledge’.

It is certainly true that science rests ultimately on what we know. That

fact is the basis of the Coperhagen point of view. However, the tremendous

successes of the classical physical theory inaugurated by Galileo, Descartes,

and Newton during the seventeenth century, had raised the hope and expec-

tation that human beings could extract from careful observation, and the

imaginative creation of testable hypotheses, a valid idea of the general na-

ture, and rules of behaviour, of the reality in which our human knowledge is

imbedded. Giving up on that hope is indeed a radical shift. On the other

hand, classical physical theory left part of reality out, namely our conscious

2

experiences. Thus it had no way to account either for the existence of our

conscious experiences or for how knowledge can reside in those experiences.

Hence bringing human experience into our understanding of reality seems to

be a step in the right direction: it might allow science to explain, eventually,

how we know what we know. But Copenhagen quantum theory is only a

half-way house: it does bring in human experience, but at the stiff price of

excluding the rest of reality.

Yet how could the renowned scientists who created Copenhagen quantum

theory ever believe, and sway most other physicists into believing, that a

complete science could leave out the physical world? It is certainly undeniable

that we can never know for sure that a proposed theory of the world around

us is really true. But that is not a sufficient reason to renounce, as a matter

of principle, the attempt to form at least a coherent idea of what the world

could be like. Clearly some extraordinarily powerful consideration was in

play.

That powerful consideration was a basic idea about the nature of phys-

ical causation that had been injected into physics by Einstein’s theory of

relativity. That idea was not working!

The problem is this. Quantum theory often entails that an act of acquir-

ing knowledge in one place instantly changes the theoretical representation

of some faraway system. Physicists were—and are—reluctant to believe that

performing a nearby act can instantly change a faraway physical reality. How-

ever, they recognize that “our knowledge” of a faraway system can instantly

change when we learn something about a nearby system. In particular, if

certain properties of two systems are known to be strongly correlated, then

finding out something about one system can tell us someing about the other.

For example, if we know that two particles start from some known point at

the same time, and then move away from that point at the same speeds,

but in opposite directions, then finding one of these particles at a certain

point allows us to ‘know’ where the other particle lies at that same instant:

it must lie at the same distance from the starting point as the observed par-

3

ticle, but in the opposite direction. In this simple case we do not think that

the act of observing the position of one particle causes the other particle to

be where it is. We realize that is only our knowledge of the faraway system

that has changed. This analogy allows us resolve, by fiat, any mystery about

an instantaneous faraway effect of a nearby act: if something faraway can

instantly be altered by a nearby act then it must be our knowledge. But then

the analog in quantum theory of the physical reality of classical physical

theory must be our knowledge.

This way of dodging the action-at-a-distance problem was challenged by

Einstein, Podolsky, and Rosen (1935) in a famous paper entitled: “Can

quantum-mechanical description of physical reality be considered complete?”

The issue was whether a theory that is specified to be merely a set of rules

about connections between human experiences can be considered to be a

complete description of physical reality. Einstein and his colleagues gave

a reasonable definition of “physical reality”, and then argued, directly from

some basic precepts of quantum theory itself, that the answer to this question

is ‘No’. But Bohr (1935) composed a subtle reply.

Given the enormity of what must exist in the universe, and the relative

smallness human knowledge, it is astonishing that, in the minds of most

physicists, Bohr prevailed over Einstein in this debate: the majority of quan-

tum physicists acquiesced to Bohr’s claim that quantum theory, regarded as

a theory about human knowledge, is a complete description of physical real-

ity. This majority opinion stems, I believe, more from the lack of a promising

alternative candidate than from any decisive logical argument.

Einstein (1951), commenting on the orthodox Copenhagen position, said:

“What I dislike about this kind of argument is the basic positivistic attitude,

which from my view is untenable, and seems to me to come to the same

thing as Berkeley’s principle, esse est percipi, “to be is to be perceived”.

Several other scientists also reject the majority opinion. For example, Murray

Gell-Mann (1979) asserts: “Niels Bohr brainwashed a whole generation into

believing that the problem was solved fifty years ago”. Gell-mann believes

4

that in order to integrate quantum theory coherently into cosmology, and to

understand the evolutionary process that has produced creatures that can

have knowledge, one needs to have a coherent theory of the evolving quantum

mechanical reality in which these creatures are imbedded.

It is in the context of such efforts to construct a more complete theory

that the significance of the experiments pertaining to quantum nonlocality

lies.

The point is this: If nature really is nonlocal, as these experiments sug-

gest, then the way is open to the development of a rationally coherent theory

of nature that integrates the subjective knowings introduced by Copenhagen

quantum theory into an objectively existing and evolving physical reality.

The basic framework is provided by the version of quantum theory con-

structed by John von Neumann (1932)

All physical theories are, of course, provisional, and subject to future re-

vision and elaboration. But at a given stage in the development of science

the contending theories can be evaluated on many grounds, such as utility,

parsimony, predictive power, explanatory power, conceptual simplicity, log-

ical coherence, and aesthetic beauty. The development of von Neumann’s

theory that I shall describe here fares well on all of these counts.

To understand von Neumann’s improvement one must appreciate the

problems with its predecessor. Copenhagen quantum theory gives special sta-

tus to measuring devices. These devices are physical systems: they are made

up of atomic constituents. But in spite of this, these devices are excluded

from the world of atomic constituents that are described in the mathematical

language of quantum theory. The measuring devices, are described, instead,

in a different language, namely by “the same means of communication as

the one used in classical physics” (Bohr 1958). This approach renders the

theory pragmatically useful but physically incoherent. It links the theory to

“our knowledge” of the measuring devices in a useful way, but disrupts the

dynamical unity of the physical world by treating in different ways different

atomic particles that are interacting with each other. This tearing apart of

5

the physical world creates huge conceptual problems, which are ducked in

the Copenhagen approach by renouncing man’s ability to understand reality.

The Copenhagen version of quantum theory is thus a hybrid of the old

familiar classical theory, which physicists were understandably reluctant to

abandon completely, and a totally new theory based on radically different

concepts. The old ideas, concepts, and language were used to describe our

experiences, but the old idea that visible objects were made up of tiny ma-

terial objects resembling miniature planets, or minute rocks, was dropped.

The observed physical world is described rather by a mathematical structure

that can best be characterized as representing information and propensities:

the information is about certain events that have occurred in the past, and

the propensities are objective tendencies pertaining to future events.

These “events” are the focal point of quantum theory: they are hap-

penings that in the Copenhagen approach are ambiguously associated both

with the “measuring devices” and with increments in the knowledge of the

observers who are examining these devices. Each increment of knowledge is

an event that updates the knowledge of the observers by bringing it in line

with the observed outcome of an event occurring at a device. The agreement

between the event at the device and the event in the mind of the observer is

to be understood in the same way as it is understood in classical physics.

But there’s the rub: the connection between human knowledge and the

physical world never has been understood in classical physics. The seven-

teenth century division between mind and matter upon which classical phys-

ically theory was erected was such a perfect cleavage that no reconciliation

has ever been achieved, in spite of tremendous efforts. Nor is such a reconcil-

iation possible within classical physics. According to that theory, the world

of matter is built out of microscopic entities whose behaviours are fixed by

interaction with their immediate neighbors. Every physical thing or activity

is just some arrangement of these local building blocks and their motions,

and all of the necessary properties of all of these physical components are

consequences of the postulated ontological and dynamical properties of the

6

tiny parts. But these properties, which are expressible in terms of numbers

assigned to space-time points, or small regions, do not entail the existence of

the defining qualities of conscious experience, which are experiential in char-

acter. Thus the experiential aspect of nature is not entailed by the principles

of classical physical theory, but must be postulated as an ad hoc supernu-

merary that makes no difference in the course of physical events. This does

not yield the conceptually unified sort of theory that physicists seek, and

provides no dynamical basis for the evolution, through natural selection, of

the experiential aspect of nature.

The fact that quantum theory is intrinsically a theory of mind-matter

interaction was not lost upon the early founders and workers. Wolfgang

Pauli, John von Neumann, and Eugene Wigner were three of the most rig-

orous thinkers of that time. They all recognized that quantum theory was

about the mind-brain connection, and they tried to develop that idea. How-

ever, most physicists were more interested in experiments on relatively simple

atomic systems, and were understandably reluctant to get sucked into the

huge question of the connection between mind and brain. Thus they were

willing to sacrifice certain formerly-held ideals of unity and completeness,

and take practical success to be the measure of good science.

This retreat both buttressed, and was buttressed by, two of the main

philosophical movements of the twentieth century. One of these, materialism-

behaviourism, effectively denies the existence of our conscious “inner lives”,

and the other, postmodern-social-constructionism, views science as a social

construct without any objective mind-independent content. The time was

not yet ripe, either philosophically or scientifically, for a serious attempt to

study the physics of mind-matter connection. Today, however, as we enter

the third millenium, there is a huge surge of interest among philosophers,

psychologists, and neuroscientists in reconnecting the aspects of nature that

were torn asunder by seventeenth century physicists.

John von Neumann was one of the most brilliant mathematicians and

logicians of his age, and he followed where the mathematics and logic led.

7

From the point of view of the mathematics of quantum theory it makes no

sense to treat a measuring device as intrisically different from the collection

of atomic constituents that make it up. A device is just another part of the

physical universe, and it should be treated as such. Moreover, the conscious

thoughts of a human observer ought to be causally connected most directly

and immediately to what is happening in his brain, not to what is happening

out at some measuring device.

The mathematical rules of quantum theory specify clearly how the mea-

suring devices are to be included in the quantum mechanically described

physical world. Von Neumann first formulated carefully the mathematical

rules of quantum theory, and then followed where that mathematics led.

It led first to the incorporation of the measuring devices into the quantum

mechanically described physical universe, and eventually to the inclusion of

everything built out of atoms and their constituents. Our bodies and brains

thus become, in von Neumann’s approach, parts of the quantum mechani-

cally described physical universe. Treating the entire physical universe in this

unified way provides a conceptually simple and logically coherent theoretical

foundation that heals the rupturing of the physical world introduced by the

Copenhagen approach. It postulates, for each observer, that each experien-

tial event is connected in a certain specified way to a corresponding brain

event. The dynamical rules that connect mind and brain are very restrictive,

and this leads to a mind-brain theory with significant explanatory power.

Von neumann showed in principle how all of the predictions of Copen-

hagen quantum theory are contained in his version. However, von Neumann

quantum theory gives, in principle, much more than Copenhagen quantum

theory can. By providing an objective description of the entire history of

the universe, rather than merely rules connecting human observations, von

Neumann’s theory provides a quantum framework for cosmological and bio-

logical evolution. And by including both brain and knowledge, and also the

dynamical laws that connect them, the theory provides a rationally coherent

dynamical framework for understanding the relationship between brain and

8

mind.

There is, however, one major obstacle: von Neumann’s theory, as he

formulated it, appears to conflict with Einstein’s theory of relativity.

Reconciliation with Relativity

Von Neumann formulated his theory in a nonrelativistic approximation:

he made no attempt to reconcile it with the empirically validated features of

Einstein’s theory of relativity.

This reconciliation is easily achieved. One can simply replace the non-

relativistic theory used by von Neumann with modern relativistic quantum

theory. This theory is called relativistic quantum field theory. The word

“field” appears here because the theory deals with such things as the quan-

tum analogs of the electric and magnetic fields. To deal with the mind-brain

interaction one needs to consider the physical processes in human brains. The

relevant quantum field theory is called quantum electrodynamics. The rele-

vant energy range is that of atomic and molecular interactions. I shall assume

that whatever high-energy theory eventually prevails in quantum physics, it

will reduce to quantum electrodynamics in this low-energy regime.

But there remains one apparent problem: von Neumann’s nonrelativistic

theory is built on the Newtonian concept of the instants of time, ‘now’,

each of which extends over all space. The evolving state of the universe,

S(t), is defined to be the state of the entire universe at the instant of time

t. Einstein’s theory of relativity rejected, at least within classical physical

theory, the idea that the Newtonian idea of the instant “now” could have

any objective meaning.

Standard formulations of relativistic quantum field theories (Tomonaga

1946 & Schwinger 1951) have effective instants “now”, namely the Tomonaga-

Schwinger surfaces σ. As Pauli once strongly emphasized to me, these sur-

faces, while they may give a certain aura of relativistic invariance, do not

differ significantly from the constant-time surfaces “now” that appear in the

Newtonian physics. All efforts to remove completely from quantum theory

the distinctive role of time, in comparison to space, have failed.

9

To obtain an objective relativistic version of von Neumann’s theory one

need merely identify the sequence of constant-time surfaces “now” in his the-

ory with a corresponding objectively defined sequence of Tomonaga-Schwinger

surfaces σ.

Giving special objective physical status to a particular sequence of space-

like surfaces does not disrupt any testable demands of the theory of relativity:

this relativistic version of von Neumann’s theory is fully compatible with the

theory of relativity at the level of empirically accessible relationships. But

the theory does conflict with a metaphysical idea spawned by the theory of

relativity, namely the idea that there is no dynamically preferred sequence of

instantaneous “nows”. The theory resurrects, at a deep level, the Newtonian

idea of instantaneous action.

The astronomical data (Smoot et al. 1992) indicates that there does

exist, in the observed universe, a preferred sequence of ‘nows’: they define the

special set of surfaces in which, for the early universe, matter was distributed

almost uniformly in mean local velocity, temperature, and density. It is

natural to assume that these empirically specified surfaces are the same as

the objective preferred surfaces “now” of von Neumann quantum theory.

Nonlocality and Relativity

von Neumann’s objective theory immediately accounts for the faster-

than-light transfer of information that seems to be entailed by the nonlocality

experiments: the outcome that appears first, in the cited experiment, occurs

in one or the other of the two Swiss villages. According to the theory, this

earlier event has an immediate effect on the evolving state of the universe,

and this change has an immediate effect on the propensities for the various

possible outcomes of the measurement performed slightly later in the other

village.

This feature—that there is some sort of objective instantaneous transfer

of information—conflicts with the spirit of the theory of relativity. However,

this quantum effect is of a subtle kind: it acts neither on matter, nor on locally

conserved energy-momentum, nor on anything else that exists in the classical

10

conception of the physical world that the theory of relativity was originally

designed to cover. It acts on a mathematical structure that represents, rather,

information and propensities.

The theory of relativity was originally formulated within classical physical

theory. This is a deterministic theory: the entire history of the universe is

completely determined by how things started out. Hence all of history can

be conceived to be laid out in a four-dimensional spacetime. The idea of

“becoming”, or of the gradual unfolding of reality, has no natural place in

this deterministic conception of the universe.

Quantum theory is a different kind of theory: it is formulated as an

indeterministic theory. Determinism is relaxed in two important ways. First,

freedom is granted to each experimenter to choose freely which experiment

he will perform, i.e., which aspect of nature he will probe; which question

he will put to nature. Then Nature is allowed to pick an outcome of the

experiment, i.e., to answer to the question. This answer is partially free: it is

subject only to certain statistical requirements. These elements of ‘freedom

of choice’, on the part of both the human participant and Nature herself,

lead to a picture of a reality that gradually unfolds in response to choices

that are not necessarily fixed by the prior physical part of reality alone.

The central roles in quantum theory of these discrete choices—of the

choices of which questions will be put to nature, and which answer nature

delivers—makes quantum theory a theory of discrete events, rather than a

theory of the continuous evolution of locally conserved matter/energy. The

basic building blocks of the new conception of nature are not objective tiny

bits of matter, but choices of questions and answers.

In view of these deep structural differences there is a question of prin-

ciple regarding how the stipulation that there can be no faster-than-light

transfer of information of any kind should be carried over from the invalid

deterministic classical theory to its indeterministic quantum successor.

The theoretical advantages of relaxing this condition are great: it pro-

vides an immediate resolution all of the causality puzzles that have blocked

11

attempts to understand physical reality, and that have led to a renunciation

of all such efforts. And it hands to us a rational theoretical basis for attacking

the underlying problem of the connection between mind and brain.

In view of these potential advantages one must ask whether it is really

beneficial for scientists to renounce for all time the aim of trying to un-

derstand the world in which we live, in order to maintain a metaphysical

prejudice that arose from a theory that is known to be fundamentally incor-

rect?

I use the term “metaphysical prejudice” because there is no theoretical

or empirical evidence that supports the non-existence of the subtle sort of

instantaneous action that is involved here. Indeed, both theory and the

nonlocality experiments, taken at face value, seem to demand it. The denial

of the possibility of such an action is a metaphysical commitment that was

useful in the context of classical physical theory. But that earlier theory

contains no counterpart of the informational structure upon which the action

in question acts.

Renouncing the endeavour to understand nature is a price too heavy to

pay to preserve a metaphysical prejudice.

Is Nonlocality Real?

I began this article with the quote from Physics Today: “Nonlocality

gets more real.” The article described experiments whose outcomes were

interpreted as empirical evidence that nature was nonlocal, in some sense.

But do nonlocality experiments of this kind provide any real evidence that

information is actually transferred over spacelike intervals? An affirmative

answer to this question would provide direct positive support for rejecting

the metaphysical prejudice in question

The evidence is very strong that the predictions of quantum theory are

valid in these experiments involving pairs of measurements performed at

essentially the same time in regions lying far apart. But the question is

this: Does the fact that the predictions of quantum theory are correct in

experiments of this kind actually show that information must be transferred

12

instantaneously, in some (Lorentz) frame of reference?

The usual arguments that connect these experiments to nonlocal action

stem from the work of John Bell (1964). What Bell did was this. He noted

that the argument of Einstein, Podolsky, and Rosen was based on a certain

assumption, namely that “Physical Reality”, whatever it was, should have at

least one key property: What is physically real in one region cannot depend

upon which experiment an experimenter in a faraway region freely chooses

to do at essentially the same instant of time. Einstein and his collaborators

showed that if this property is valid then the physical reality in a certain

region must include, or specify, the values that certain unperformed mea-

surements would have revealed if they had been performed. However, these

virtual outcomes are not defined within the quantum framework. Thus the

Einstein-Podolsky-Rosen argument, if correct, would prove that the quantum

framework cannot be a complete description of physical reality.

Bohr countered this argument by rejecting the claimed key property of

physical reality: he denied the claim pertaining to no instantaneous action

at a distance. His rebuttal is quite subtle, and not wholly convincing.

Bell found a more direct way to counter the argument of Einstein, Podol-

sky, and Rosen. He accepted both a strong version of what Einstein, Podol-

sky and Rosen were trying to prove, namely that there was an underlying

physical reality (hidden-variables) that determined the results that all of the

pertinent unperformed measurements would have if they were performed. He

also assumed, with Einstein, Podolsky and Rosen. that there was no instan-

taneous action at a distance. Finally, Bell assumed, as did all the disputants,

that the predictions of quantum theory were correct. He showed that these

assumptions led to a mathematical contradiction.

This contradiction showed that something was wrong with the argument

of Einstein, Podolsky, and Rosen. But it does not fix where the trouble

lies. Does the trouble lie with the assumption that there is no instantaneous

action at a distance? Or does it lie in the hidden-variable assumption that

“outcomes” of unperformed measurements exist?

13

Orthodox quantum theory gives an unequivocal answer: the hidden-

variable assumption that outcomes of unperformed measurements exist is

wrong: it directly contradicts quantum philosophy!

This way of understanding Bell’s result immediately disposes of any sug-

gestion that the validity of the predictions of quantum theory entails the

existence of instantaneous or faster-than-light influences.

Bell, and others who followed his “hidden-variable” approach, (Clauser

1978) later used assumptions that appear weaker than this original one (Bell

1987). However, this later assumption is essentially the same as the earlier

one: it turns out to entail (Stapp 1979 & Fine 1982) the possibility of defining

numbers that could specify, simultaneously, the values that all the relevant

unperformed measurements would reveal if they were to be performed. But,

as just mentioned, one of the basic precepts quantum philosophy is that such

numbers do not exist.

Eliminating Hidden Variables

The purpose of Bell’s argument was different from that of Einstein, Podol-

sky, and Rosen, and the logical demands are different. The challenge faced by

Einstein and his colleagues was to mount an argument built directly on the

orthodox quantum principles themselves. For only by proceeding in this way

could they get a logical hook on the quantum physicists that they wanted to

convince.

This demand posed a serious problem for Einstein and co-workers. Their

argument, like Bell’s, involved a consideration of the values that unperformed

measurements would reveal if they were to be performed. Indeed, it was

precisely the Copenhagen claim that such values do not exist that Einstein

and company wanted to prove untenable. But they needed to establish the

existence of such values without begging the question, i.e., without making

an assumption that was equivalent to what the were trying to show.

The strategy of Einstein et. al. was to prove the existence of such values

by using only quantum precepts themselves, plus the seemingly secure idea

from the theory of relativity that what is physically real ‘here and now’

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cannot be influenced by what a faraway experimenter chooses to do ‘now’.

This strategy succeeded: Bohr (1935) was forced into an awkward position

of rejecting Einstein’s premise that “physical reality” could not be influenced

by what a faraway experimenter chooses to do:

“...there is essentally the question of an influence on the very conditions

which define the possible types of predictions regarding future behavior of

the system. Since these conditions constitute an inherent element of any

phenomena to which the term ‘physically reality’ can be properly attached we

see that the argument of mentioned authors does not justify their conclusion

that quantum-mechanical description is essentially incomplete.”

I shall pursue here a strategy similar to that of Einstein and his col-

leagues, and will be led to a conclusion similar to Bohr’s, namely the failure

of Einstein’s assumption that physical reality cannot be influenced from afar.

The first step is to establish a logical toe-hold by bringing in some the

notion of “what would happen” under a condition that is not actually real-

ized. This is the essential key step, because all proofs of nonlocality depend

basically on using some such “counterfactuality”. But any such step stands

in danger of conflicting with quantum philosophy. So one must secure this

introduction of “counterfactuality” in order to get off the ground.

A very limited, but sufficient, notion of counterfactuality can be brought

into the theoretical analysis by combining two ideas that are embraced by

Copenhagen philosophy. The first of these is the freedom of experimenters to

choose which measurements they will perform. In the words of Bohr (1958):

“The freedom of experimentation, presupposed in classical physics, is of

course retained and corresponds to the free choice of experimental arrange-

ments for which the mathematical structure of the quantum mechanical for-

malism offers the appropriate latitude.”

This assumption is important for Bohr’s notion of complementarity: some

information about all the possible choices is simultaneously present in the

quantum state, and Bohr wanted to provide the possibility that any one of

the mutually exclusive alternatives might be pertinent. Whichever choice the

15

experimenter eventually makes, the associated set of predictions is assumed

to hold.

The second idea is the condition of no backward-in-time causation. Ac-

cording to quantum thinking, experimenters are to be considered free to

choose which measurement they will perform. Moreover, if an outcome of

a measurement appears to an observer at a time earlier than some time T ,

then this outcome can be considered to be fixed and settled at that time

T , independently of which experiment will be freely chosen and performed

by another experimenter at a time later than T : the later choice is allowed

go either way without disturbing the outcome that has already appeared to

observers at an earlier time.

I shall make the weak assumption that this no-backward-in-time-influence

condition holds for at least one coordinate system (x,y,z,t).

These two conditions are, I believe, completely compatible with quantum

thinking, and are a normal part of orthodox quantum thinking. They con-

tradict no quantum precept or combination of quantum predictions. They,

by themselves, lead to no contradiction. But they do introduce into the

theoretical framework a very limited notion of a result of an unperformed

measurement, namely the result of a measurement that is actually performed

in one region at an earlier time t coupled with the measurement NOT per-

formed later by some faraway experimenter. My assumption is that this

earlier outcome, which is actually observed by someone, can be treated as

existing independently of which of the two alternative choices will made by

the experimenter in the later region, even though only one of the two later

options can be realized. This assumption of no influence backward in time

constitutes the small element of counterfactuality that provides the needed

logical toe-hold.

The Hardy Experimental Setup

My aim is to show that the assumptions described above lead to the need

for some sort of instantaneous (or faster-than-light) transfer of information

about which choice is made by an experimenter in one region into a second

16

region that is spacelike separated from the first. To do this it is easiest to con-

sider an experiment of the kind first discussed by Lucien Hardy (1993). The

setup is basically similar to the ones considered in proofs of Bell’s theorem.

There are two spacetime regions, L and R, that are “spacelike separated”.

This condition means that the two regions are situated far apart in space

relative to their extensions in time, so that no point in either region can be

reached from any point in the other without moving either faster than the

speed of light or backward in time. This means also that in some frame of

reference, which I take to be the coordinate system (x,y,z,t) mentioned above,

the region L lies at times greater than time T , and region R lies earlier than

time T .

In each region an experimenter freely chooses between two possible ex-

periments. Each experiment will, if chosen, be performed within that region,

and its outcome will appear to observers within that region. Thus neither

choice can affect anything located in the other region without there being

some influence that acts faster than the speed of light or backward in time.

The argument involves four predictions made by quantum theory under

the Hardy conditions. These conditions and predictions are described in Box

1.

——————————————————————–

Box 1: Predictions of quantum theory for the Hardy experi-

ment.

The two possible experiments in region L are labelled L1 and L2.

The two possible experiments in region R are labelled R1 and R2.

The two possible outcomes of L1 are labelled L1+ and L1-, etc.

The Hardy setup involves a laser down-conversion source that emits a pair

of correlated photons. The experimental conditions are such that quantum

theory makes the following four predictions:

1. If (L1,R2) is performed and L1- appears in L then R2+ must appear

in R.

17

2. If (L2,R2) is performed and R2+ appears in R then L2+ must appear in

L.

3. If (L2,R1) is performed and L2+ appears in L then R1- must appear in

R.

4. If (L1,R1) is performed and L1- appears in L then R1+ appears sometimes

in R.

The three words “must” mean that the specified outcome is predicted to

occur with certainty (i.e., probability unity).

—————————————————————————

Two Simple Conclusions

It is easy to deduce from our assumptions two simple conclusions.

Recall that region R lies earlier than time T , and that region L lies later

than time T .

Suppose the actually selected pair of experiments is (R2, L1), and that

the outcome L1- appears in region L. Then prediction 1 of quantum theory

entails that R2+ must have already appeared in R prior to time T . The

no-backward-in-time-influence condition then entails that this outcome R2+

was fixed and settled prior to time T , independently of which way the later

free choice in L will eventually go: the outcome in region R at the earlier

time would still be R2+ even if the later free choice had gone the other way,

and L2 had been chosen instead of L1.

Under this alternative condition (L2,R2,R2+) the experiment L1 would

not be performed, and there would be no physical reality corresponding to

its outcome. But the actual outcome in R would still be R2+, and we

are assuming that the predictions of quantum theory will hold no matter

which of the two experiments is eventually performed later in L. Prediction

2 of quantum theory asserts that it must be L2+. This yields the following

conclusion:

Assertion A(R2):

If (R2,L1) is performed and outcome L1- appears in region L, then if

18

the choice in L had gone the other way, and L2, instead of L1, had been

performed in L then outcome L2+ would have appeared there.

Because we have two predictions that hold with certainty, and the two

strong assumptions of ‘free choice’ and ‘no backward causation’, it is not

surprising that we have been able to derive this conclusion. In an essentially

deterministic context we are often able to deduce from the outcome of one

measurement what would have happened if we had made, instead, another

measurement. Indeed, if knowing the later actual outcome allows one to

know what some earlier condition must have been, and if this earlier condi-

tion entails a unique result of the later alternative measurement, then one

can conclude from knowledge of the later actual outcome what would have

happened if, instead, the later alternative measurement had been performed.

This is about the simplest possible example of counterfactual reasoning.

Consider next the same assertion, but with R2 replaced by R1:

Assertion A(R1):

If (R1,L1) is performed and outcome L1- appears in region L, then if

the choice in L had gone the other way, and L2, instead of L1, had been

performed in L then outcome L2+ would have appeared there.

This assertion cannot be true. The fourth prediction of quantum theory

asserts that under the specified conditions, L1- and R1, the outcome R1+

appears sometimes in R. The no backward-in-time-influence condition en-

sures that this earlier fact would not be altered if the later choice in region

L had been L2. But A(R1) asserts that under this altered condition L2+

would appear in L. The third prediction then entails that R1- must always

appear in R. But that contradicts the earlier assertion that R1+ sometimes

appears in R.

The fact that A(R2) is true and A(R1) can be stated briefly:

R2 implies LS is true, and

R1 implies LS is false,

where LS is the statement

LS:“If experiment L1 is performed in region L and gives outcome L1- in

19

region L then if, instead, experiment L2 had been performed in region L the

outcome in region L would have been L2+.”

These two conditions, which follow from ‘orthodox’ assumptions, impose

a severe condition on any putative model of reality. It imposes, first of all,

a sharp constraint that ties Nature’s choice of outcome under one condition

set up in L to Nature’s choice of outcome under a different condition set up

in L. And it asserts, moreover, that this constraint depends upon what the

experimenter decides to do in a region R that is spacelike separated from L.

I believe that it is impossible for any putative model of reality to satisfy

these conditions if the information about the free choice made by the exper-

imenter in R is not available in L. Lacking any model that could satisfy this

condition without allowing the information about the choice made in R to

be present in L one must allow this faster-than-light transfer of information.

This extensive discussion of nonlocality is intended to make thoroughly ra-

tional the critical assumption of the objective interpretation von Neumann’s

formulation of quantum theory that is being developed here, namely the as-

sumption that there is a preferred set of successive instants “now” associated

with the evolving objective quantum state of the universe.

The Physical World as Active Information

Von Neumann quantum theory is designed to yield all the predictions of

Copenhagen quantum theory. But those predictions are about connections

between increments of human knowledge. Hence the von Neumann theory

must necessarily encompass those increments of knowledge. Von Neumann’s

theory is, in fact, essentially a theory of the interaction of these subjective

realities with an evolving objective physical universe.

The evolution of this physical universe involves three related processes.

The first is the deterministic evolution of the state of the physical universe. It

is controlled by the Schroedinger equation of relativistic quantum field theory.

This process is a local dynamical process, with all the causal connections

arising solely from interactions between neighboring localized microscopic

elements. However, this local process holds only during the intervals between

20

quantum events.

Each of these quantum events involves two other processes. The first is a

choice of a Yes-No question by the mind-brain system. The second of these

two processes is a choice by Nature of an answer, either Yes or No, to this

question. This second choice is partially free: it is a random choice, subject

to the statistical rules of quantum theory. The first choice is the analog in

von Neumann theory of an essential process in Copenhagen quantum theory,

namely the free choice made by the experimenter as to which aspect of nature

is going to be probed. This choice of which aspect of nature is going to be

probed, i.e., of which specific question is going to be put to nature, is an

essential element of quantum theory: the quantum statistical rules cannot

be applied until, and unless, some specific question is first selected.

In Copenhagen quantum theory this choice is made by an experimenter,

and this experimenter lies outside the system governed by the quantum rules.

This feature of Copenhagen quantum theory is not altered in the transition

to von Neumann quantum theory: choice by a person of which question will

be put to nature is not controlled by any rules that are known or understood

within contempory physics. This choice on the part of the mind-brain system

that constitutes the person, is, in this specific sense, a free choice: it is not

governed by the physical laws, as they are currently understood.

Only Yes-No questions are permitted: all other possibilities can be re-

duced to these. Thus each answer, Yes or No, injects one “bit” of information

into the quantum universe. These bits of information are stored in the evolv-

ing objective quantum state of the universe, which is a compendium of these

bits of information. The quantum state state of the universe is therefore an

informational structure. But this stored compendium of bits of information

has causal power: it specifies the propensities (objective tendencies) that are

associated with the two alternative possible answers to the next question put

to Nature.

This essential feature of the quantum state, that it has causal efficacy, in

the form of propensities for future events, I shall express by saying that the

21

quantum state represents Active Information.

Once the physical world is understood in this way, as a stored com-

pendium of locally efficacious bits of information, the instantaneous transfers

of information along the preferred surfaces “now” can be understood to be

changes, not in personal human knowledge, but in the state of objective

active information.

Mind-Brain Interaction

Von Neumann quantum theory—particularly as explicated by Wigner

(1987)—is essentially a theory of the interaction between the evolving phys-

ical universe and the sequence of events that constitute our streams of con-

sciousness. The theory specifies the general form of the interaction between

our subjective conscious knowings and activities in our brains. However, the

details need to be filled in, predictions deduced, and comparisons made to

empirical data.

A key feature of quantum brain dynamics is the strong action of the

environment upon the brain. This action creates a powerful tendency for the

brain to transform almost instantly (See Tegmark 2000) into an ensemble of

components, each of which is very similar to an entire classically-described

brain. I assume that this transformation does indeed occur, and exploit it in

two important ways. First, this close connection to classical physics makes

the dynamics easy to describe: classical language and imagery can be used

to describe in familar terms how the brain behaves. Second, this description

in familar classical terms makes it easy to identify the important ways in

which this behaviour differs from what classical physics would predict.

A key micro-property of the human brain pertains to the migration of

calcium ions from micro-channels through which these ions enter the interior

of the nerve terminals to the sites where they trigger the release of a vesicle

of neuro-transmitter. The quantum mechanical rules entail (Stapp 1993,

2000) that each release of a vesicle of neurotransmitter causes the quantum

state of the brain to split into different classically describable components,

or branches.

22

Evolutionary considerations entail that the brain must keep the brain-

body functioning in a coordinated way, and more specifically, must plan and

put into effect, in each normally encountered situation, a single coherent

course of action that meets the needs of that person. Due to the quantum

splitting mentioned above, the quantum state of the brain will tend to decom-

pose into components that specify alternative possible courses of action. In

short, the purely mechanical evolution in accordance with the Schroedinger

equation will normally cause the brain to evolve into a growing ensemble of

alternative possible branches, each of which is essentially an entire classically

described brain that specifies a possible appropriate plan or course of action.

This ensemble that constitutes the quantum brain is mathematically sim-

ilar to an ensemble that occurs in a classical treatment when one takes into

account the uncertainties in our knowledge of the intitial conditions of the

particles and fields that constitute the classical representation of a brain.

This close connection between what quantum theory gives and what classi-

cal physics gives is the basic reason why von Neumann quantum theory is

able to produce all of the correct predictions of classical physics. To unearth

quantum effects one can start from this superficial similarity at the lowest-

order approximation that yields the classical results, and then dig deeper.

In the quantum treatment there is a second part of the dynamics: the

ordered sequence of mind-brain events. The effect of each such event is to

discard part of the ensemble that constitutes the quantum brain, and thus

reduce that prior ensemble to a subensemble.

Three problems then arise: 1) How is the retained subensemble picked

out from the prior ensemble? 2) What is the character of the conscious

experience that constitutes the mind part of this mind-brain event? 3) What

role does this conscious experience, itself, play in this reduction process?

The answers to these questions are determined, in general terms, by von

Neumann’s basic dynamical assumption. In the present case this assumption

amounts to this: the physical event reduces the initial ensemble that con-

stitutes the brain prior to the event to the subensemble consisting of those

23

branches that are compatible with the associated conscious event. This rule

is just the application at the level of the brain of the same rule that Copen-

hagen quantum theory applies at the level of the device.

This dynamical connection means that, during an interval of conscious

thinking, the brain changes by an alternation between two processes. The

first is the generation, by a local deterministic mechanical rule, of an ex-

panding profusion of alternative possible branches, with each branch corre-

sponding to an entire classically describable brain embodying some specific

possible course of action. The brain is the entire ensemble of these separate

quasi-classical branches. The second process involves an event that has both

physical and experiential aspects. The physical aspect, or event, chops off

all branches that are incompatible with the associated conscious aspect, or

event. For example, if the conscious event is the experiencing of some feature

of the physical world, then the associated physical event would be the updat-

ing of the brain’s representation of that aspect of the physical world. This

updating of the brain is achieved by discarding from the ensemble of quasi-

classical brain states all those branches in which the brain’s representation of

the physical world is incompatible with the information that is consciously

experienced.

This connection is similar to a functionalist account of consciouness. But

here it is just a consequence of the basic principles of physics, rather than

some peculiar extra ad hoc structure that is not logically entailed by the

basic physics.

The quantum brain is an ensemble of quasi-classical components. It was

just noted that this structure is similar to something that occurs in classical

statistical mechanics, namely a “classical statistical ensemble.” But a clas-

sical statistical ensemble, though structurally similar to a quantum brain, is

fundamentally a different kind of thing. It is a representation of a set of truly

distinct possibilities, only one of which is real. A classical statistical ensemble

is used when a person does not know which of the conceivable possibilities

is real, but can assign a ‘probability’ to each possibility. In contrast, all of

24

the elements of the ensemble that constitute a quantum brain are equally

real: no choice has yet been made among them, Consequently, and this is

the key point, the entire ensemble acts as a whole in the determination of

the upcoming mind-brain event.

A conscious thought is associated with the actualization of some macro-

scopic quasi-stable features of the brain. Thus the reduction event is a macro-

scopic happening. And this event involves, dynamically, the entire ensemble.

In the corresponding classical model each element of the ensemble evolves

independently, in accordance with a micro-local law of motion that involves

just that one branch alone. Thus there are crucial dynamical differences

between the quantum and classical dynamics.

The only element of dynamical freedom in the theory—insofar as we leave

out Nature’s choices—is the choice made by the quantum processor of which

question it will ask next, and when it will ask it. These are the only inputs

from mind to brain dynamics. This severe restriction on the role of mind is

what gives the theory its predictive power.

Asking a question about something is closely connected to focussing one’s

attention on it. Attending to something is the act of directing one’s mental

power to some task. This task might be to update one’s representation of

some feature of the surrounding world, or to plan or execute some other sort

of mental or physical action.

The key question is then this: Can freedom merely to choose which ques-

tion is asked, and when it is asked, lead to any statistically significant influ-

ence of mind on the behaviour of the brain?

The answer is Yes!

There is an important and well studied effect in quantum theory that

depends on the timings of the reduction events arising from the queries put

to nature. It is called the Quantum Zeno Effect. It is not diminished by

interaction with the environment (Stapp 1999, 2000).

The effect is simple. If the same question is put to nature sufficiently

rapidly and the initial answer is Yes, then any noise-induced diffusion, or

25

force-induced motion, of the system away from the subensemble where the

answer is Yes will be suppressed: the system will tend to be confined to

the subensemble where the answer is Yes. The effect is sometimes jokingly

called the “watched pot” effect: according to the old adage “A watched pot

never boils”; just looking at it keeps it from changing. Similarly, a state

can be pulled along gradually by posing a rapid sequence of questions that

change sufficiently slowly over time. In short, according to the dynamical

laws of quantum mechanics, the freedom to choose which questions are put

to nature, and when they are asked, allows mind to exert a strong influence

on the behaviour of the brain.

But what freedom is given to the human mind?

According to this theory, the freedom given to Nature herself is quite

limited: Nature simply gives a Yes or No answer to a question posed by

a subsystem. It seems reasonable to restrict in a similar way the choice

given to a human mind. The simplest way to do this is to allow brain to

select from among all experientially distinquishable possible courses of action

specified by the quasi-classical components that comprise it, the one with the

greatest statistical weight. The mathematical structure of quantum theory

is naturally suited to this task. The choice given to mind can then be to say

Yes or No: to consent to, or veto, this possible course of action. The question

will be simply: Will the ‘optimal’ course of action produced by brain process

be pursued or not. The positive answer will cause the branches of the brain

that are incompatible with this positive answer to be discarded; the negative

answer will cause the branches of the brain that are incompatible with that

negative answer to be discarded.

The timings of the questions must also be specified. I assume that the

rate at which the questions are asked can be increased by conscious effort.

Then the quantum Zeno effect will allow mind to keep attention focussed on

a task, and oppose both the random wanderings generated by uncertainties

and noise, and also any directed tendency that is generated by the mechanical

forces that enter into the Schroedinger equation, and that would tend to shift

26

the state of the brain out of the subspace corresponding to the answer ‘Yes’.

5. Explanatory Power

Does this theory explain anything?

This theory was already in place (Stapp 1999) when a colleague brought to

my attention some passages from “Psychology: The Briefer Course”, written

by William James (1892). In the final section of the chapter on Attention

James writes:

“I have spoken as if our attention were wholly determined by neural con-

ditions. I believe that the array of things we can attend to is so determined.

No object can catch our attention except by the neural machinery. But the

amount of the attention which an object receives after it has caught our at-

tention is another question. It often takes effort to keep mind upon it. We

feel that we can make more or less of the effort as we choose. If this feeling

be not deceptive, if our effort be a spiritual force, and an indeterminate one,

then of course it contributes coequally with the cerebral conditions to the

result. Though it introduce no new idea, it will deepen and prolong the stay

in consciousness of innumerable ideas which else would fade more quickly

away. The delay thus gained might not be more than a second in duration—

but that second may be critical; for in the rising and falling considerations

in the mind, where two associated systems of them are nearly in equilibrium

it is often a matter of but a second more or less of attention at the outset,

whether one system shall gain force to occupy the field and develop itself and

exclude the other, or be excluded itself by the other. When developed it may

make us act, and that act may seal our doom. When we come to the chapter

on the Will we shall see that the whole drama of the voluntary life hinges

on the attention, slightly more or slightly less, which rival motor ideas may

receive. ...”

In the chapter on Will, in the section entitled “Volitional effort is effort

of attention” James writes:

“Thus we find that we reach the heart of our inquiry into volition when

we ask by what process is it that the thought of any given action comes to

27

prevail stably in the mind.”

and later

“The essential achievement of the will, in short, when it is most ‘volun-

tary,’ is to attend to a difficult object and hold it fast before the mind. ...

Effort of attention is thus the essential phenomenon of will.”

Still later, James says:

“Consent to the idea’s undivided presence, this is effort’s sole achieve-

ment.” ...“Everywhere, then, the function of effort is the same: to keep

affirming and adopting the thought which, if left to itself, would slip away.”

This description of the effect of mind on the course of mind-brain process

is remarkably in line with the what arose from a purely theoretical consid-

eration of the quantum physics of this process. The connections discerned

by psychologists are explained of the basis of the same dynamical principles

that explain the underlying atomic phenomena. Thus the whole range of

science, from atomic physics to mind-brain dynamics, is brought together in

a single rationally coherent theory of an evolving cosmos that consists of a

physical reality, made of objective knowledge or information, interacting via

the quantum laws with our streams of conscious thoughts.

Much experimental work on attention and effort has occurred since the

time of William James. That work has been hampered by the nonexistence

of any putative physical theory that purports to explain how our conscious

experiences influence activities in our brains. The behaviourist approach,

which dominated psychological during the first half of the twentieth century,

and which essentially abolished, in this field, not only the use of introspective

data but also the very concept of consciousness, was surely motivated in part

by the apparent implication of classical physics that consciousness was either

just a feature of a mechanical brain, or had no effect at all on the brain or

body. In either of these two cases human consciousness could be eliminated

from a scientific account human behaviour.

The failure of the behaviourist programs led to the rehabilitation of “at-

tention” during the early fifties, and many hundreds of experiments have

28

been performed during the past fifty years for the purpose of investigating

empirically those aspects of human behaviour that we ordinarily link to our

consciousness.

Harold Pashler’s book “The Psychology of Attention” (Pashler 1998) de-

scribes a great deal of this empirical work, and also the intertwined theo-

retical efforts to understand the nature of an information-processing system

that could account for the intricate details of the objective data. Two key

concepts are the notions of a processing “Capacity” and of “Attention”. The

latter is associated with an internally directed selection between different

possible allocations of the available processing “Capacity”. A third concept

is ”Effort”, which is linked to incentives, and to reports by subjects of “trying

harder”.

Pashler organizes his discussion by separating perceptual processing from

postperceptual processing. The former covers processing that, first of all,

identifies such basic physical properties of stimuli as location, color, loudness,

and pitch, and, secondly, identifies stimuli in terms of categories of meaning.

The postperceptual process covers the tasks of producing motor actions and

cognitive action beyond mere categorical identification. Pashler emphasizes

(p. 33) that “the empirical findings of attention studies specifically argue

for a distinction between perceptual limitations and more central limitations

involved in thought and the planning of action.” The existence of these

two different processes, with different characteristics, is a principal theme of

Pashler’s book (Pashler 1998 p. 33, 263, 293, 317, 404).

In the quantum theory of mind-brain being described here there are two

separate processes. First, there is the unconscious mechanical brain process

governed by the Schroedinger equation. It involves processing units that

are represented by complex patterns of neural activity (or, more generally,

of brain activity) and subunits within these units that allow ”association”:

each unit tends to be activated by the activation of several of its subunits.

The mechanical brain evolves by the dynamical interplay of these associative

units. Each quasi-classical element of the ensemble that constitutes the brain

29

creates, on the basis of clues, or cues, coming from various sources, a plan

for a possible coherent course of action. Quantum uncertainties entail that a

host of different possibilities will emerge. (Stapp 1993, 2000). This mechan-

ical phase of the processing already involves some selectivity, because the

various input clues contribute either more or less to the emergent brain pro-

cess according to the degree to which these inputs activate, via associations,

the patterns that survive and turn into the plan of action.

This conception of brain dynamics seems to accommodate all of the per-

ceptual aspects of the data described by Pashler. But it is the high-level

processing, which is more closely linked to our conscious thinking, that is of

prime interest here. The data pertaining to that second process is the focus

of part II of Pashler’s book.

Conscious process has, according to the physics-based theory described

here, several distinctive characteristics. It consists of a sequence of discrete

events each of which consents, on the basis of a high-level evaluation that

accesses the whole brain, to an integrated course of action presented by

brain. The rapidity of these events can be increased with effort. Effort-

induced speed-up of the rate of occurrence of these events can, by means

of the quantum Zeno effect, keep attention focussed on a task. Between

100 and 300 msec of consent seem to be needed to fix a plan of action, and

initiate it. Effort can, by increasing the number of events per second, increase

the input into brain activity of the high-level evaluation and control that

characterizes this process. Each conscious event picks out from the multitude

of quasi-classical possibilities created by brain process the subensemble that

is compatible with this conscious event. This correspondence, between a

conscious event and the associated physical event—via a reduction of the

prior physical ensemble to the subensemble compatible with the experience of

the observer—is the core interpretive postulate of quantum theory. Applied

at the level of the device it is the basis of Copenhagen quantum theory. Thus

von Neumann-Wigner quantum theory applies at the level of the brain the

same reduction principle that is used by quantum physicists to account both

30

for the approximate validity of the laws of classical physics, and also for the

deviations from those laws that produce quantum phenomena.

Examination of Pashler’s book shows that this physics-based theory ac-

commodates naturally for all of the complex structural features of the empir-

ical data that he describes. He emphasizes (p. 33) a specific finding: strong

empirical evidence for what he calls a central processing bottleneck associ-

ated with the attentive selection of a motor action. This kind of bottleneck is

what the physics-based theory predicts: the bottleneck is the single sequence

of mind-brain quantum events that von Neumann-Wigner quantum theory

is built upon.

Pashler (p. 279) describes four empirical signatures for this kind of bottle-

neck, and describes the experimental confirmation of each of them. Much of

part II of Pashler’s book is a massing of evidence that supports the existence

of a central process of this general kind.

This bottleneck is not automatic within classical physics. A classical

model could easily produce simultaneously two responses in different modal-

ities, say vocal and manual, to two different stimuli arriving via two different

modalities, say auditory and tactile: the two processes could proceed via dy-

namically independent routes. Pashler (p. 308) notes that the bottleneck is

undiminished in split-brain patients performing two tasks that, at the level

of input and output, seem to be confined to different hemispheres.

Pashler states (p. 293) “The conclusion that there is a central bottleneck

in the selection of action should not be confused with the ... debate (about

perceptual-level process) described in chapter 1. The finding that people

seem unable to select two responses at the same time does not dispute the fact

that they also have limitations in perceptual processing...”. I have already

mentioned the independent selectivity injected into brain dynamics by the

purely mechanical part of the quantum mind-brain process.

The queuing effect for the mind-controlled motor responses does not ex-

clude interference between brain processes that are similar to each other, and

hence that use common brain mechanisms. Pashler (p. 297) notes this dis-

31

tinction, and says “the principles governing queuing seem indifferent to neural

overlap of any sort studied so far.” He also cites evidence that suggests that

the hypthetical timer of brain activity associated with the cerebellum “is

basically independent of the central response-selection bottleneck.”(p. 298)

The important point here is that there is in principle, in the quantum

model, an essential dynamical difference between the unconscious processing

carried out by the Schroedinger evolution, which generates via a local process

an expanding collection of classically conceivable possible courses of action,

and the process associated with the sequence of conscious events that consti-

tutes a stream of consciousness. The former are not limited by the queuing

effect, because all of the possibilities develop in parallel, whereas the latter

do form elements of a single queue. The experiments cited by Pashler all

seem to support this clear prediction of the quantum approach.

An interesting experiment mentioned by Pashler involves the simultane-

ous tasks of doing an IQ test and giving a foot response to a rapidly presented

sequences of tones of either 2000 or 250 Hz. The subject’s mental age, as

measured by the IQ test, was reduced from adult to 8 years. (p. 299)

This result supports the prediction of quantum theory that the bottleneck

pertains to both ‘intelligent’ behaviour, which requires conscious processing,

and selection of motor response, to the extent that the latter is consciously

experienced as either an intended or recognized updating of the person’s

body and/or environment.

The quantum approach constitutes, in practice, a different way of looking

at the data: it separates the conscious process of selecting and recognizing

the intended or actual reality from the unconscious process of generating

possible courses of action, and puts aside, temporarily, but in a rationally

coherent quantum-based way, the question of exactly how the choices asso-

ciated with the conscious decisions are made. The point is that quantum

theory suggests that this latter process of making a discrete choice is gov-

erned by a dynamics that is more complex than the mechanical process of

grinding out possibilities, and that one therefore ought not be locked into a

32

narrow mechanical perspective that makes the dynamics that underlies the

two processes the same, and the same as the idealized dynamical process that

classical physical theory was based upon.

Another interesting experiment showed that, when performing at max-

imum speed, with fixed accuracy, subjects produced responses at the same

rate whether performing one task or two simultaneously: the limited capacity

to produce responses can be divided between two simultaneously performed

tasks. (p. 301)

Pashler also notes (p. 348) that “Recent results strengthen the case for

central interference even further, concluding that memory retrieval is sub-

ject to the same discrete processing bottleneck that prevents simultaneous

response selection in two speeded choice tasks.”

In the section on “Mental Effort” Pashler reports that “incentives to per-

form especially well lead subjects to improve both speed and accuracy”, and

that the motivation had “greater effects on the more cognitively complex

activity”. This is what would be expected if incentives lead to effort that

produces increased rapidity of the events, each of which injects into the phys-

ical process, via quantum selection and reduction, bits of control information

that reflect high-level evaluation.

In a classical model one would expect that a speed-up of the high-level

process would be accompanied by an increase in the consumption of metabolic

energy, as measured by blood flow and glucose uptake. But Pashler suggests,

cautiously, that this is not what the data indicate. In any case, the quantum

reduction processes do not themselves consume metabolic energy, so there is,

in the quantum model, no direct need for a speed up in conscious processing

itself to be accompanied by an increased energy consumption in the parts of

the brain directly associated with this processing.

Studies of sleep-deprived subjects suggest that in these cases “effort works

to counteract low arousal”. If arousal is essentially the rate of occurrence of

conscious events then this result is what the quantum model would predict.

Pashler notes that “Performing two tasks at the same time, for example,

33

almost invariably... produces poorer performance in a task and increases

ratings in effortfulness.” And “Increasing the rate at which events occur

in experimenter-paced tasks often increases effort ratings without affecting

performance”. “Increasing incentives often raises workload ratings and per-

formance at the same time.” All of these empirical connections are in line

with the general principle that effort increases the rate of conscious events,

each of which inputs a high-level evaluation and a selection of, or focussing

on, a course of action, and that this resource can be divided between tasks.

Of course, some similar sort of structure could presumably be worked into

a classical model. So the naturalness of the quantum explanations of these

empirical facts is not a decisive consideration. In the context of classical

modelling the success of the quantum model suggests the possible virtue

of conceptually separating the brain process into two processes in the way

that the quantum model automatically does. But a general theory of nature

that automatically gives a restrictive form is superior to one that needs to

introduce it ad hoc.

Additional supporting evidence comes from the studies of the effect of

the conscious process upon the storage of information in short-term memory.

According to the physics-based theory, the conscious process merely actu-

alizes a course of action, which then develops automatically, with perhaps

some occasional monitoring. Thus if one sets in place the activity of retain-

ing in memory a certain sequence of stimuli, then this activity can persist

undiminished while the central processor is engaged in another task. This is

what the data indicate.

Pashler remarks that ”These conclusions contradict the remarkably widespread

assumption that short-term memory capacity can be equated with, or used

as a measure of, central resources.”(p.341). In the theory outlined here short-

term memory is stored in patterns of brain activity, whereas consciousness is

associated with the selection of a subensemble of quasi-classical states that

are compatible with the consciously accepted course of action. This sepa-

ration seems to account for the large amount of detailed data that bears

34

on this question of the connection of short-term-memory to consciousness

(p.337-341).

Deliberate storage in, or retrieval from, long-term memory requires fo-

cussed attention, and hence conscious effort. These processes should, ac-

cording to the theory, use part of the limited processing capacity, and hence

be detrimentally affected by a competing task that makes sufficient concur-

rent demands on the central resources. On the other hand, “perceptual”

processing that involves conceptual categorization and identification with-

out conscious choice should not interfere with tasks that do consume central

processing capacity. These expectations are what the evidence appears to

confirm: “the entirety of...front-end processing are modality specific and op-

erate independent of the sort of single-channel central processing that limits

retrieval and the control of action. This includes not only perceptual analysis

but also storae in STM (short term memory) and whatever may feed back

to change the allocation of perceptual attention itself.” (p. 353)

Pashler describes a result dating from the nineteenth century: mental ex-

ertion reduces the amount of physical force that a person can apply. He notes

that “This puzzling phenomena remains unexplained.” (p. 387). However,

it is an automatic consequence of the physics-based theory: creating physi-

cal force by muscle contraction requires an effort that opposes the physical

tendencies generated by the Schroedinger equation. This opposing tendency

is produced by the quantum Zeno effect, and is roughly proportional to the

number of bits per second of central processing capacity that is devoted to

the task. So if part of this processing capacity is directed to another task,

then the applied force will diminish.

Pashler speculates on the possibility of a neurophysiological explanation

of the facts he describes, but notes that the parallel, as opposed to serial,

operation of the two mechanisms leads, in the classical neurophysiological

approach, to the questions of what makes these two mechanisms so different,

and what the connection between them is (p.354-6, 386-7)

After analyzing various possible mechanisms that could cause the central

35

bottleneck, Pashler (p.307-8) says “the question of why this should be the

case is quite puzzling.” Thus the fact that this bottleneck, and its basic

properties, come out naturally from the same laws that explain the complex

empirical evidence in the fields of classical and quantum physics, rather than

from some ad hoc adjustment of theory to data, means that the theory has

significant explanatory power.

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